A very annoying fault!!!

[NEW65]

I've just overhauled an hermle 1151-050/85cm. I fitted at least 12 bushings. The strike train and quarter train are like new, full power has been restore
The time train is the issue! I fitted the pendulum and set it going but next morning it had stopped. I adjusted the verge slightly and set it going again but once again it stopped! There was lots of overswing!
I then slightly opened up the verge pivot holes and tried again and the amplitude increased so I thought I'd fixed it! However next morning it had stopped again!
I then removed the cannon pinion and minute wheel and star cam, just leaving the handshaft arbor. I started the pendulum again and it stopped 2 hours later!
At this stage I'm losing the will to live. Bear in mind that after I had overhauled this movement I checked all the gears to ensure they were not tight. All were loose when I did the drop test!
However I then discovered that when I gently pressed on the front of the handshaft arbor the pendulum starting losing power ; when I pulled the handshaft arbor back power was restored to the pendulum again !
I took the movement apart to inspect the handshaft arbor/wheel/pinion but couldn't see any faults at all.
I spent 15 hours rebuilding that movement so I'm very disappointed with this fault. I've never had anything like this happen to me before but I won't be giving up yet!
Any ideas please reply.
Thanks chaps

 

[Vernon]

You could have a taper on the pivot or bushing. Check the pivot with a micrometer against a light source. If you use broaches then that can create taper.
Vernon

 

[disciple_dan]

Did you bush the rear plate on T3? If so, do you chamfer the inside of your bushings? I've had problems similar to that. Danny.

 

[Willie X]

You have probably already checked (or replaced) the back center shaft bushing. If not, you may want to try a new bushing there. If so, make sure the new bushing has a small chamfer on the inside face.

The problem you have is exactly what made me start chamfering all new and some old bushings.

A somewhat tapered, or bugle shaped, pivot shoulder can work it's way over and stick like a Morse taper. A slight wiggle and it's all fine, until it happens again.

I had this trouble with an old New Haven kitchen clock and I worked with it for months. Turned out to be the front escape wheel bushing that was replaced 20 years ago. It seemed fine but would grab that pivot once in a blue moon.

Best test: the 'sandwich drop', combined with the 'slow roll' test. keep in mind that center wheel takes a long time to make one turn ...

Good luck, Willie

 

[POWERSTROKE]

I'd check the escape wheel too. I had an old Hubert Herr with great overswing that had a tooth or tow on the escape wheel that wasn't just right. It was maddening.

 

[JimmyOz]

Another thing to try is to set it aside and do something else, then when you go back it just may present itself to you, sometime clearing your mind is good.

 

[RJSoftware]

I keep telling you all about the high speed test, but judging from lack of response not many care for it. The low speed test is a norm here, where the suspect train is given just a few clicks, enough to get trane rolling. So one repeats the slow test till stoppage keeps happening same spot.
This is good for a bad tooth.

The high speed test (hst) is almost identical, both low and high remove anchor/palette so the movement can free wheel. But the high speed test does more. Stop the escape wheel or fly, then fully wind and let her rip. Chime and music tranes is simply allowed to free wheel by restraint of stopping levers.

The main thing to do is listen. Become familiar with acceptable and suspect sound. I use to think rumbling and occasional pops was sign of a bad trane. But what I have learned to listen for is synchronized repeating sound. One of the main culprits is bent pivot and/or bent arbor. This results in loose to binding mesh resulting in a sound/speed variance that is easy to hear. The higher the frequency the more higher up the trane and vice versa. One of the biggest advantage is revealing bent arbors low in the trane.

A person can spend many days/hours when a gear has slightly bent arbor/pivot low on the trane because the clock can run for days then repeatedly stop. A bent arbor on a low gear causes a rotation from loose to tight in the span of many days, causing a lack of hope.

"It ran fine for days and days, now it wont run for 2 minutes and keeps getting worse. What is going on? "

But look, do the high speed test and a bent arbor/pivot low in the trane is revealed in a brief moment. Think of how common a jarring broken main spring is and realize all that sudden explosive power usually does something. So this is common.

You may think, "I'll just chuck all the gears in the lathe and check for true". But why not identify which gear, right away, first?

You can easily add to hst other test like positional to test for binding. By changing gravity direction may accent sound of problem gear.

Another hst addition is slightly squeeze plates at different areas to test for lack of endshake binding. An area can be sensitive to reducing endshake distance. Often due to a coned pivot. So say you suspect the minute arbors back pivot is coned. While doing hst, press fingernail on hand end of minute arbor, If it comes to dead stop you know where to look, but if it keeps cranking on then I doubt it's the problem.

Like everything there are subtle nuances. Sometimes it doesn't always work, but it's just another tool to help.

Listen for the repeat sound then synchronize the sound to the same spinning gear.

 

[shutterbug]

I suspect that the rear pivot of your center wheel is tapered. You may have to reshape it. The alternative would be opening the bushing a bit, but that would be less desired than fixing the problem.

 

[Dave T]

Good information in this thread. Hope I can remember it next time I run into this problem. I've got rid of clocks that wouldn't run because of issues with the hands, and I've never known the problem might be caused by the bushings.

 

[Mike Phelan]

Wow! 12 bushes For those sorts of faults I do this:
(1) Let springs right down.
(2) Remove pallets.
(3) Wind all trains half a turn.
(4) Note on each train where it stops (felt marker)
Repeat 1 to 4 and see which wheel where it stops - the one that's stopping in the same place is your culprit.

 

[NEW65]

Big thanks to all the replies.
I fitted a bushing for the rear handshaft and shamfered it. The handshaft has the right amount of end play and is nice and free. (Well, it easily passed the drop test ). I refitted the time train gears only and set the movement going. Pendulum amplitude was stronger than ever. I returned next morning but sadly it had stopped again! I couldn't believe it.
Here's a further update on my findings:
When I pushed the pendulum to restart the train it was totally out of beat so I made an adjustment and set the pendulum going again. However, this time when I put my finger on the tip of the handshaft and pushed inwards there was no loss in power and the pendulum was unaffected!
I repeated the above test 4 hours later but this time the pendulum tick went quiet , and lost power?! I pulled the handshaft back again and power was restored. Its so confusing. I've lost hours of my time on this movement. This problem is completely new , I've never had a problem like this before.
I guess I will have to check out the shape of the rear handshaft pivot now to see if it's coned?
Yes, I do use broaches to open up the bushings , I've always used them and never had a problem but I do see your point Vernon.
Willie, I now know how you felt when this problem happened to you. To be honest it's knocked my confidence quite a lot and I'll be concerned from now on when preparing other movements in case it happens again!
I have noted everyones suggestions, so hopegully I'll get to the bottom of this annoying problem soon... and Jimmy you're right... sometimes walking away and taking a break really helps. I find that a good night's sleep is also good. Finding faults uses up so much time!
I'm not giving up. I fitted too many bushings to walk away

 

[Willie X]

You'll figure it out. Might be one of the smaller pivots nearer the top. They can be a bear to work with, so small. Willie

 

[NEW65]

Cheers Willie. So when I push the handshaft inwards I guess indirectly through friction contact, the smaller gears are also pushed slightly in the same direction?

 

[Bruce Alexander]

Hey New65.

When the movement stalls, with straight tweezers, try gently checking each gear for power starting with the EW and working your way down the Train to the power source.

Sounds like a real hair puller!

Good luck with it.

 

[RJSoftware]

Wow! 12 bushes For those sorts of faults I do this:
(1) Let springs right down.
(2) Remove pallets.
(3) Wind all trains half a turn.
(4) Note on each train where it stops (felt marker)
Repeat 1 to 4 and see which wheel where it stops - the one that's stopping in the same place is your culprit.

This is the LOW SPEED TEST. A long established test. Have you ever tried HIGH SPEED TEST?

One huge glaring problem with low speed test is if a pivot or arbor is only slightly bent then the movement may stop on a various range of teeth. The mesh may vary enough to sometimes squeak by or not.

The low speed test fails the lower the affected gears are. Giving only a few clicks might not be enough power to overcome a binding lower mesh. And if you're convinced enough to blindly blame a higher mesh then you might as well marker up the whole gear.

Plus...! as the movement winds down from hst, you get a bird's eye view of power transitioning from full to empty. The slow transition allows you to see more. Especially bent arbors.

To OP:
If I don't spot anything from hst I then do lst. The only thing after that is the bushing replacement is not located proper, the original location.

Broaching the bushing hole more open is bad form. You can walk the hole ever so slightly. But keep in mind you don't want to remove any material in the bushing hole on the side that prevents the mesh binding deeper. So for example you have a driving gear pushing a pinion causing a binding mesh. You walk the driving gear's bushing hole ever so slightly opposite. You walk by slightly cutting side away from pinion mesh side.

To walk, insert broach fully then pull back slightly, you can mark broach with tape for an insertion gauge. Push broach toward desired direction with 2 fingers. One on each side of plate, applying pressure toward desired location and paying attention to insertion level. Twist broach with other hand. Using a bench vice to

What happens is, even though you slightly missed the true location and had created too tight a mesh, the opened opposite side helps mesh to float past. But this varies, sometimes fails anyway.

If that fails, insert a blank bushing (no hole). Align front and back plates together, use other mating bushing hole to locate and use broach to mark pin prick. Use smaller/smallest bit you have, drill hole. Broach to fit pivot, 5 degrees lean all directions.

If you can't do this because other mating hole is wrong location too, then you need clock depthing tool.

 

[Mike Phelan]

Hi RJ,
I'm always a bit scary about letting trains run at high speed - no pallets and no flies - as I never know what state the pivots are in, even after putting oil in there could be abrasive muck there.
Chacun a son gout, i suppose.

 

[RJSoftware]

Hi RJ,
I'm always a bit scary about letting trains run at high speed - no pallets and no flies - as I never know what state the pivots are in, even after putting oil in there could be abrasive muck there.
Chacun a son gout, i suppose.

Understood, the flys I keep in, just rig stopping levers to not stop. If the speed of the train seems too intense you can intermittently stop ew till the mainspring power is less. You can saturate the bushings with oil on upper end of train to avoid abrasion.

As long as there is enough power so that you can listen to rotation of main wheel. It's quite common to have hidden damage from exploding mainspring. On some a bent arbor or even barrel is not obvious. On those the mesh rolls from shallow to deep. Deep robs the power and you can actually hear the movement speed up and slow down with the rotation of the main wheel. The hst is such a quick and practical way to see/hear.

 

[Thomas Sanguigni]

Chauncey Jerome believed in the HST. He used it also for cleaning a dirty movement. Of course, movements were only a few years old back then!

 

[Kison]

I hate when issues like this come about. When all the other mentioned advice fails, I resort to taking all the wheels out except for two meshing wheels at a time and checking for binding. So first, I’ll just put the main wheel and second, and rotate the main wheel trying to feel for a point at which they bind. Then I’ll remove the main wheel and just test the meshing of the second wheel and center shaft, repeating this process for every pair of meshing wheels and pinions that mesh. It’s a tedious process that sometimes works and sometimes doesn’t. When it does work, it’s usually because there was a bushing I put in that was too off from center and causes binding every so often. Wish I had more to help/say other than condolences for your taxed mind! Good luck!

 

[Willie X]

RJ's just mentioned the HST. This is the very best for spotting things that are bent, like: pivots, wheels, pinion wires, arbors, teeth, etc.

RJ focused on the sounds but if you look straight down into the top of the movement while it's running free, you can often see all kinds of wonkyness!

Willie X

 

[RJSoftware]

RJ's just mentioned the HST. This is the very best for spotting things that are bent, like: pivots, wheels, pinion wires, arbors, teeth, etc.

RJ focused on the sounds but if you look straight down into the top of the movement while it's running free, you can often see all kinds of wonkyness!

Willie X

Yea, if I see a fast spinning arbor, a light reflection on arbor looks fuzzy. But these days a lot is fuzzy. Left eye has a mean cataract. But I can see out my right. But doc says it's got a cataract too. Sucks gettin older...!

 

[Mike Phelan]

RJ,
My wife got one eye done last year and she has much better vision now - it was quick and locally done. Mine will need them done in a year or so.

 

[NEW65]

Thanks for the excellent advice RJ and to everyone else. I will do the checks you suggested. Hopefully I'll get to the bottom of this soon. I guess it could be a depthing issue but the crazy thing is that the movement has now been ticking away for 2 days and not stopped!!! I just have the time train between the plates.
However I cannot possibly rely on this movement behaving now. I need to find out what was causing the problem. When I first set it going and it stopped I thought it may have been a foreign object in the works but when I took it apart I found nothing , all the gears were clean. No bent pivots either.
Yes, it can be very annoying when this sort of thing happens. The movement was going to be fitted in a clock that was due out this weekend so I've had to prepare another 1151/85cm which also required a large number of bushings!
I have to say that we clock repairers need to stay patient in this job.
Thanks chaps.
I appreciate the great advice from all of you.
Simon

 

[RJSoftware]

Life is a complicated...

 

[RJSoftware]

.

 

[RJSoftware]

Think of how tiny the area of a proper mesh is. The tiny pinion teeth can only handle 90% engagement. 10% airspace is so teeth surfaces can slide across each other. Can you really see that small? Maybe.

I like the idea of using tweezers to test each wheel from escape wheel down. Kinda like mouse trap. Work the way down till it springs to life. A good way to do upper gears. Another tool in my tool box (Thanks Bruce).